Android Question OkHttpUtils2 + FirebaseAdMob2

Hi everyone, why when I use the OkHttpUtils2 and FirebaseAdMob2 libraries does the application get an error like the following:

"
Dex merge Error
Error: Cannot fit requested classes in a single dex file (# methods: 74932 > 65536). Try supplying a main-dex list
Compilation failed
Exception in thread "main" java.lang.RuntimeException: com.android.tools.r8.CompilationFailedException: Compilation failed to complete, position: null
at com.android.tools.r8.internal.vj.a(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:98)
at com.android.tools.r8.D8.main(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:4)
Caused by: com.android.tools.r8.CompilationFailedException: Compilation failed to complete, position: null
at Version.fakeStackEntry(Version_3.3.20-dev+aosp1.java:0)
at com.android.tools.r8.internal.vj.a(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:75)
at com.android.tools.r8.internal.vj.a(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:28)
at com.android.tools.r8.internal.vj.a(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:27)
at com.android.tools.r8.internal.vj.b(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:2)
at com.android.tools.r8.D8.a(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:22)
at com.android.tools.r8.D8.a(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:17)
at com.android.tools.r8.internal.vj.a(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:85)
... 1 more
Caused by: com.android.tools.r8.internal.f: Cannot fit requested classes in a single dex file (# methods: 74932 > 65536)
at com.android.tools.r8.internal.YS.a(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:14)
at com.android.tools.r8.internal.YS.a(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:22)
at com.android.tools.r8.internal.v20.a(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:565)
at com.android.tools.r8.internal.r20.a(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:7)
at com.android.tools.r8.internal.D2.a(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:335)
at com.android.tools.r8.internal.D2.a(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:412)
at com.android.tools.r8.D8.d(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:794)
at com.android.tools.r8.D8.c(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:1)
at com.android.tools.r8.internal.vj.a(R8_3.3.20-dev+aosp1_dd4c01853fd917497aef2d09abff533f0d25b062517ea74449d40e1778a34753:24)
... 5 more
"

Sorry for my bad english (Google Translate)